


In the Deep End

by BluebellDestroyerOfWorlds



Category: DCU, DCU (Comics)
Genre: Also Jason in Newt Scamander, Alternative Universe - Merepeople, Bruce Wayne Is Worse At Feelings, Dick Grayson is a Ray of Sunshine, Forgive Me, How Do I Tag, I didn't mean for this to be sweet, I have no idea if any of this is good, Jason Todd is Bad at Feelings, Jason is being kind of dumb, M/M, Mer!AU, Navy, Pirates, Slade Wilson is Creepily Nice, SladinWeek, Tell me if this is okay, but still Jason hopefully, if i'm honest, mer!Slade, or month, the title is a pun
Language: English
Status: Completed
Published: 2019-11-03
Updated: 2019-11-03
Packaged: 2021-01-21 09:34:07
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 8,403
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21297305
Author URL: https://archiveofourown.org/users/BluebellDestroyerOfWorlds/pseuds/BluebellDestroyerOfWorlds
Summary: 'The lieutenant nearly relaxed. “So… You’re not going to kill me?”The mer shook it's head. “Not yet, little human.”'Jason finds himself a little out of depth (yes, I'm milking this pun for all it's worth), when he sneaks away from his fleet and manages to fall into the infamous killer mer, Deathstroke's, lair. Something close to fluff (but not quite) follows.
Relationships: Jason Todd/Slade Wilson
Comments: 17
Kudos: 250





	In the Deep End

**Author's Note:**

  * Inspired by [Big Fish in a Small Pond](https://archiveofourown.org/works/19812949) by [Skalidra](https://archiveofourown.org/users/Skalidra/pseuds/Skalidra). 

> This is basically what happens when I watch Master and Commander, read 'Big Fish in a Small Pond' (written by Skalidra, please read it, if you haven't, it's great!) and finish reading another volume of Red Hood and the Outlaws in one week.
> 
> Also, yeah, the idea was meant for the second day of Sladin Week, but I've given up on trying to be on time with those fics (not that I can be anymore), so I'm using the ideas I had when I saw the prompts as something I can write over the next few weeks.
> 
> Enjoy!

The first thing Jason noticed was that it was dark. The second thing was that he was wet and cold. The third thing was that everything hurt like fucking hell. Slowly, he turned over, groaning, only to get a mouthful of seawater. Spluttering he sat up, his bruised limbs screaming at him to stop moving, and looked around. He was barely able to make out anything in the gloom. The ridges of tall, glistening wet rocks jutting up around him, were outlined by a dim white light, falling through what looked to be a gaping hole in the sky. Shit. He was in a cave.

He tried to get up, but the sharp, stabbing pain, that shot through his calf and knee had him on his ass again, before he could even get halfway upright. Wincing, he let his hand trail gingerly along the offending limb. It was broken. There was a dull ache on the back of his skull, too. He felt panic and slowly growing dizziness clouding his brain, before everything went pitch black.

._.

“_C’mon, Bruce… You said this would be an exploration mission, not just you hunting down some pirate that’s only going to escape again! Not that that’s really working out, so far we’ve been stuck in this fucking piece of drift wood for two months!” The lieutenant thumped his fist against the table and the others sitting at it looked at him in various shades of shock, annoyance and sympathy._

“_Lieutenant Todd...” There was a clear warning in that tone, but Jason ignored it._

“_What?! There’s an island just under a mile from us! An island I’m pretty sure no one has been on for centuries! Who knows what we could find there!” Jason was nearly shouting now, he had enough of this. Enough of being stuck here without the slightest puff of wind to move them an inch closer to their nebulous destination. “I don’t see why I can’t relieve a few men from having nothing to do but sit around all day with their dicks in their hands-” There were a few snorts at that, accompanied by a tutting from the older officers. “and take a small boat to-”_

“_Jason!” Everyone fell silent and Jason was embarrassed by the way his posture automatically snapped into straight-backed perfect little soldier boy at the sound of that tone. Bruce looked fucking furious. “You are suggesting putting a group of my men at risk just so you can draw a few beetles! That island is mer territory! You know how vicious those creatures are about defending their homes! You are not a foot soldier anymore, Jason, we don’t have back-up, no one on this ship is expendable!”_

“_But-” Jason began, before Bruce stopped him, his voice a rough growl now._

“_You may be my son, lieutenant, but I will not be giving you any special treatment. I am your commodore! You will follow my orders! We do not have the time or the resources for your damned hobby!” _

_Jason stared at him, anger and frustration clear on his face. He got up, his chair hitting the floor with a crash, as he stormed out of the officer’s dinning room. Eyes followed him and his elder brother even started to get up to accompany him, before Bruce put a hand on his sleeve._

_Dick did find him later, of course, after the meal, coming into his quarters without knocking and sitting down on the chest placed beside the younger man’s hammock, where Jason swayed, ignoring him in favour of angrily turning the pages of one of the many natural biology books he had stashed away in his cabin. “You know he didn’t mean it, right?” The man finally broke the uncomfortable silence with. “It’s just the weather that’s got him on edge. He loves that you’re interested in all this stuff.” Dick gestured around the room, at the various animal drawings on the wall and little cages and jars containing lizards and beetles and other small creatures that Jason had discovered hiding in a few of the ship’s many nooks and crannies. “He’s just worried, you know? The mer that lives around here is pretty well known for going out of it’s way to kill humans. Trust me, I’ve seen the bastard at it and it’s not exactly pretty.”_

“_Oh, c’mon!” Jason slammed the book shut. “Deathstroke hasn’t been sighted for years now, for all we know that thing could be dead, or it could have left! Bruce’s just worried I’ll do something to compromise his stupid mission...”_

“_Well...” Dick began, but stopped when Jason glared angrily at him._

“_Oh fuck off, Dickbrain!” he snarled, folding his arms around his chest. “That was one time! We can’t all be as perfect as you, captain!” His tone was meant to be mocking, but there was something bitter and hurt there, too._

_Dick winced and looked guiltily at the floor. He’d been awarded the title a few months ago now, which meant that their ship was, when Bruce wasn’t using it as a place to coordinate the entire fleet, technically under his to command, which meant Jason was, too. It’d been a long time coming, but that didn’t mean that every time Jason caught sight of the insignia on his sleeve he didn’t feel a surge of jealousy for the older man. Bruce may claim to love all his sons equally, but Jason knew he’d sooner blow up his own ship that give Jason a title like that. Not that he wanted it, of course, but still… If Dick had asked to go out and poke around the island, Bruce would have probably let him take an entire crew with him._

“_Jason...” Dick’s sad voice cut through his train of thought. “You know that’s not what this is about. B loves you and he cares about you. He just doesn’t want you to do anything reckless...” There was something very close to pity in his voice now._

_Jason’s scowl got even darker. “Yeah, well, when he can say that stuff himself, without needing a fucking interpreter, then I might actually give a shit about what he thinks!” He got up suddenly, swinging his legs out of hammock in a way that almost made his boots collide with Dick’s head, if he hadn’t ducked fast enough. He strode towards the door and swung it open, gesturing to the corridor outside. “Until then, kindly fuck right off! I’m feeling the sudden, unstoppable urge to draw a few stupid, fucking beetles!”_

_After Dick had left, giving him a hurt puppy look that Jason was sure would haunt him when he’d stopped feeling so fucking angry, Jason didn’t end up drawing a beetle. Instead he started to pack. He sealed his sketchbook, along with the lead pencils, in a watertight pouch, managed to sneak into the kitchen and convince the old cook, Alfred, to give him some food by pretending he was still hungry after not finishing dinner with the other officers. Roy had been worryingly ready to give him a few small weapons from the armoury without asking too many questions and taking one of the boats hanging from the side of the ship had been way too easy, even if he had the cover of night. It had been slow going when it came to rowing across the far-too-still ocean to the distant island. But he’d reached it by daybreak and it had been more than worth it. The shellfish, sea slugs and small fish he’d collected in the pools all around the rocky beach was enough to keep him scribbling notes for days, but he’s been even more delighted upon reaching the main land. Insects, snakes and lizards were abundant on the rocky landscape and he was pretty sure he’d never seen quite a number of them before, not even in illustrations. But the crowning moment was when he saw a large, extremely odd-looking, flightless bird bounding across the landscape. He’d tried to draw it, but, upon seeing him, the creature had rushed off, Jason hot on it’s tail. He’d left most of his supplies and captured animals on a cliff-top, taking only his sketchbook and a water pouch with him, to pursue the bird, fully intending to collect the other supplies later, once he’d at least finished a sketch of the wonderful beast. And then he’d fallen down a hole and knocked himself out._

_._._

Light burned into Jason’s closed lids, not blinding but sufficient to wake him. He opened his eyes blearily and looked around again. Surprise, surprise, he was still in a cave, not that he’d really expected much else. The light shining through the large hole he’d tumbled down meant that he could actually see it, he noticed that there was something strangely pretty about his new prison. It was actually quite beautiful. The pale, almost turquoise rock walls and ceiling was hollowed out in beautiful curves and dark blue lines and rings indicated the layers of pressed stone that had been carved away by the ocean. The tall rocks that were placed randomly across the floor of the cave where of the same stone, as was the smooth, almost level floor, that was covered by a layer of salt water. Jason could see deeper pools scattered across the smooth stone, large and small patches of dark blue that Jason watched warily. There was no telling how deep they could be. The main thing that struck Jason as odd was the lack of vegetation, or sea creatures in the cave, but he shrugged it off, looking at the sky again. It was obviously daybreak outside and Jason wondered vaguely if Bruce had sent out a search party yet. He felt a wave of frustration rush over him and nearly screamed every curse he knew at the growing sun. He was going to be in so much shit for this…

Suddenly, his attention was drawn to a sound coming from behind a group of tall rocks to his right. A squelching, tearing, sucking sort of sound that immediately had him on edge. He inched closer to the rocks, wincing every time his bad leg dragged over the floor. Behind the rocks there was a pool, larger than the others and deeper, by the looks of it, too. Jason peered around the rocks, dragging himself a little closer until he saw a a faint tint of red staining the water in the pool. He stopped, still listening to the sounds. Feeding. Something was definitely eating something. By the colour of the blood, Jason would have to guess freshly caught fish. He inched closer, his heart pounding and then he froze.

Right at the edge of the pool, only a few meters away from where Jason was hiding, was a mer. It was huge, bigger than the ones that Jason had occasionally seen stealing food from the nets at Gotham’s harbour, even bigger than the ones he’d fought beside Bruce, when they attacked his fleet last summer. It had it’s back turned to Jason and he could see those long, razor sharp claws holding down a humpback anglerfish, while it devoured it. Jason was by no means a small man, but he could tell that this thing could overpower him without much effort, nothing but pure muscle was under that layer of dark, slate-grey skin. From what Jason could see of it’s torso he was pretty sure that it could snap him in two. Even more worrying was the far from small amount of scars on it’s skin accompanied by the long mane of silver hair that pooled in the water behind it. Mers healed fast, but their fights still left scars and from what Jason knew of their culture, a mer defeated in a fair fight would have their hair clipped almost to the scalp, as a sign of shame. This mer didn’t look like that had happened to him in a very long time, no matter the obviously high number of battles it had been in.

Jason gulped, a lot louder than he had meant to. The mer froze, the anglerfish still moving feebly In it’s grip. Panic was gripping every inch of Jason and he could feel the blood pumping in his ears. It wasn’t that he was necessarily afraid of death, in fact Bruce always berated him for being a reckless, suicidal idiot on the battlefield. But the clean passing of a bullet through his skull was nothing compared to having his flesh being brutally ripped from his bones and eaten while he was still breathing. He’d seen survivors of a mer attack up close and the remains of those unlucky enough to become their prey. He couldn’t think of a more painful way to go.

He started to crawl back, trying not to make any sound, but he wasn’t looking at where we was putting his hands and he couldn’t help but breathe a quiet “Fuck!”, when his hand slipped into a small pool, making a small splash.

There was a much larger splash and the sound of claws dragging a huge weight onto the smooth stone floor. Jason was scrabbling towards the wall as fast as he could now, his leg aching and his arms straining to pull himself forward. He’d seen a mer crawl across a ships deck in a matter of seconds and he wasn’t taking any chances. Finally his back hit the wall and he looked desperately for something he could climb up onto. There was a smooth ledge and then another, about a meter above him. He got up, steadying himself on his good leg and grabbing at the ledge, hoisting himself up. He was almost there, when claws sunk into his injured calf and he let out a scream that echoed around the walls of the large cave. He looked down. The mer was right below him, swiping at his legs with those huge talons. His boot connected with it’s face and he heard a grunt of pain, he used the few seconds of the beast’s distraction to pull his legs up onto the ledge, then hoist himself up onto the higher one, followed again by his legs. Tears were pouring down his cheeks as the salt water burned at his bleeding and battered calf and he could feel hysteria flooding his veins.

He looked down, only to make sure the mer couldn’t follow him and the colour still left in his panic-stricken face drained away in a matter of seconds. He recognized the beast. The one everyone called Deathstroke. Nearly every sailor in the world could describe the thing staring up at him, even if they’d never seen it themselves. Stories of its brutal attacks had been around for centuries now and it was even rumoured that the mer was immortal. A single, pale blue eye looked up at him, regarding his distress with a sort of cool interest, the other eyes was hidden by a strip of soaked black clothe. Black claws took another experimental swipe at him. Now that the creature was in the shallows, he could see that long, thick tail, too. It was covered in large black scales, which, unlike the smaller slate-grey ones of it it’s torso, were tipped with a sort of copper shine, that glittered in the light. Jason might have found the animal beautiful, if it didn’t so obviously want to kill him.

To his horror, the beast looked him dead in the eye and raised the claws covered in his blood to it’s mouth, a long, black tongue slipped out and ran down them, lapping at the crimson liquid with delight. It smirked at Jason, eye narrowing.

He wasn’t sure if it was the panic, the earlier concussion or the fact that he was loosing a lot of blood that made him faint this time, but before he knew it darkness was, for the third time, clouding his vision.

._.

When he woke up again, the sun was at the highest point in the sky. He shifted and felt some sort of grip on his injured leg, he tried to pull away, but it wouldn’t budge. His eyes shot open. Something cold pooled in his stomach as he saw it. The mer had managed to pull itself up on the ledge just below Jason and was studying his injured calf with curiosity. Jason noticed with dread that the wound was clean now and that the mer’s mouth was covered with blood.

He tried to stay still, not to show the mer that he was conscious, maybe it would leave him alone, if he didn’t give it enough sport. But as he forcibly kept himself still, his muscles clenched and he hissed at the stab of pain that shot up his calf once more. The mer looked at him and he let out a breath, shutting his eyes and waiting for sharp teeth to sink into his flesh. Instead something cool and slippery lapped at his calf. He cracked open an eye. The mer was licking his wound, lapping up the blood that had spilled as his muscles had tensed. It looked up at him again and he stared back, then it cocked it’s head curiously. “Why are you not healing?” The voice was raspy and growling, the mer was clearly not used to using its vocal cords.

Jason’s eyes went wide. “You… You just talked… How? Mers can’t-” he cut himself off, as the mer hissed in annoyance.

“I have been alive since before your ancestors could swim, hatchling… Your language is hardly complicated.” The mer bared his teeth, the razor sharp points stopping Jason from pointing out that that wasn’t very hard, seeing as most of his ancestors probably couldn’t swim. “Now answer me.”

“It’s only been a day since I fell down here.” Jason answered, his head still ringing from the strangeness of this situation. “I don’t know how it is with mer, but humans don’t heal that fast.”

The mer tutted and rolled it’s eye. “Weak...” It hissed and then it moved, pulling itself up so that it’s face was level with Jason’s “Why are you in my cave, weak human?”

“Okay, hey!” Jason growled, his temper canceling out his common sense for the time being. “Just because my wounds don’t magically heal within a couple of hours does not make me fucking weak! Not everyone has freakishly thick skin like you!” The mer’s mouth quirked at the corners and Jason continued. “And trust me, I don’t want to be here. I was just exploring the island and I fell down a hole.” he finished lamely, his heartbeat picking up as the mer leaned closer to him.

“Your are weak.” The mer grabbed him with a speed and grace that Jason would not have expected from someone with so much bulk. He was pinned to the stone wall before he could stop to think and no matter how much he struggled, the mer’s grip remained vice-like around his wrists and on his neck. “Weak and stupid.” The mer was inches from his face now, he smelled of salt water, blood and something a lot like gunpowder. “This island has been mine for almost a century now, you should know better than to come here...”

“How the fuck was I supposed to know you’re still here?! No one’s seen you for years, I thought-”

“No. You did not.” The mer interrupted him. “If you had, you would not be here.” It’s eye flashed towards the gap in the ceiling. “That’s quite a large hole to miss, little human. Are your eyes not functional?”

“At least I got two of them!” Jason snarled, really not thinking now, he had been complained at and berated too fucking much over the past few days and he didn’t need some great big monster telling the same thing Bruce probably would if he ever got out of this alive.

There was a low, dangerous hiss from the mer and Jason froze. Shit. Okay, so mer could be effected by insults. Fuck. Fuck. Fuck. Cool breath cascaded onto his face and he shuddered, his eyes shuting again. “Say that again, hatchling...” the creature breathed.

“Fuck. I’m sorry, I didn’t mean to offend you. I’m sure you lost your eye in some heroic battle.” There was another, drawn out hiss, the hand around his throat tightened and Jason started to panic. “Or not. Please- Please don’t eat me.”

The fucking animal laughed at him. Or at least that’s what Jason thought it was. The tone and rhythm was a little off. Jason opened his eyes to find the mer’s shoulders shaking and an unmistakable smirk on it’s lips.

“Okay, fucking stop that. I don’t particularly like being laughed at when I’m scared for my life over here.” He told the mer irritably, glaring at it.

“Please don’t eat me...” The mer mimicked and Jason started to feel very hot around the ears and cheeks. “Pathetic. Mer don’t feast on the injured, hatchling. We prefer those of you who can actually put up a fight.”

The lieutenant nearly relaxed. “So… You’re not going to kill me?”

The mer shook it’s head. “Not yet, little human.”

“I’m not that little, you know.” Jason said, offended, and the mer laughed again. “Yeah, I told you to fucking stop that. I’m serious. I’m actually a lot bigger than most humans out there.”

The mer smirked at him, but stopped laughing. “You’re still a lot smaller than me, little human. A lot weaker and younger and that is really what counts at this moment, wouldn’t you agree?” The way the mer purred out the words and the way his eye stayed locked on Jason’s face had him on edge.

“I suppose.” he muttered and tried to press himself closer to the wall.

“You’re scared.” The mer stated, curiously, drawing even closer himself. Jason’s breath hitched and he looked at him incredulously.

“No shit, I’m scared. I’m unarmed and trapped in a cave with one of the most deadly mers in the fucking ocean.” he hissed, bristling. Christ, this thing really knew nothing about personal space.

The mer looked a little confused. “But I said I would not eat you yet.” it pointed out, tightening it’s grip on Jason.

He winced. “Yeah, thanks for that. Now could you let me go, please? You’re hurting me.” The grip eased a little, then lifted entirely and to Jason’s great surprise the mer pushed itself off the wall of the cave and leapt into the nearest pool, landing with barely a splash, before resurfacing. “Showoff...” Jason muttered, as it watched him make a far less elegant descent onto the stone floor. He bound his leg as best he could, ripping pieces from his shirt, before looking around the space, purposefully ignoring the mer, who after looking at Jason liked he’d gone mad, while he bandaged himself, went back to eating the anglerfish.

He spent the rest of the evening trying to climb up the sides of the cave and get back out the hole he had fallen through, getting increasingly pissed off at the mer’s quite laughing every time he fell down. “Well? How do you get out of here?!” he demanded, finally, glaring at the beast, who had rested it’s head on the side of the pool, watching him.

The mer cocked his head towards the pool. “There are tunnels underwater. I come here through them.” he said, simply and Jason let out a groan, sitting down on the floor, leaning against the wall and rubbing his leg.

“How long are these tunnels?” he asked.

“Very.”

“Well, it’s a crying shame human’s haven’t mastered breathing underwater, isn’t it?” Jason growled, glaring at the sea creature.

“Oh I don’t think that would matter either way.” The mer chuckled. “It’s not like your going anywhere with that leg.”

“You’re enjoying this, aren’t you?” Jason hissed, angrily. The mer didn’t answer him, just grinned and leapt up out of the water for a moment, before vanishing under the surface.

Jason was half glad that he didn’t come back, he’d needed a piss for the last hour or so and he didn’t really feel like exposing his genitals to the mer. Plus some of the insults he shouted at the mer after it had disappeared had been eye-related and that hadn’t go down very well last time.

He found a flat rock, that was above the water level and lay down on it, using his water pouch as a pillow and curling up into a ball. He was wet and pretty cold and he knew that would only get worse once it got dark, so he was determined to fall asleep before then. It was surprisingly easy, really, he was exhausted from everything that had happened that day and it took him minutes to start drifting off. Before his mind went blank, he thought he heard a faint splash somewhere and the sound of something sharp scraping against stone, somewhere quite close to him.

._.

Jason felt a lot warmer when he woke up and there was something heavy pressing against his front and around his waist. He opened his eyes and scrunched his face up as he was met with blackness. Something was covering his eyes. He pulled his head back and sunshine hit him right in his eyes, he blinked, annoyed and looked forward. In front of him, deep grey scales where rising and falling in slow, rhythmic bursts. He looked up, tentatively and, yes, Deathstroke was lying right in front of him. Jason glanced around. His head was resting on one of the mer’s arms, while the other was slung protectively around his waist. He’d managed to wrap one of his legs around the large tail sometime in the night and a blush rose in his cheeks as he found his hand tangled with the mer’s mane.

It took a relatively long time to get out of the mer’s grasp without waking it- him? Jason was pretty sure that the mer was male, he had a beard after all, but Jason couldn’t see any sort of genitals. Not that he’d actually looked, obviously.

Jason noticed that the mer had moved him off his rock at some point and directly under the hole he’d fallen through, which explained the warmth. Mers were cold-blooded, as far as he knew, so he must rely on the sun for some of his energy. Just as Jason finished that thought, the mer flexed his arms, grasping at where Jason had been and letting out a soft, maybe even disappointed, hiss, before rolling over onto his back and letting the sunlight play across his chest. Jason wondered if his eye-lid was thick enough to shield his eye from light and not disturb his sleep. Maybe, he certainly wasn’t reacting to the rays of light shining directly at his face.

Jason automatically looked around for his sketchbook and saw the watertight pouch he kept it in lying on the flat rock he’d fallen asleep on. He limped over to it and sat down, before pulling out the book and finding a blank page. He wasn’t sure how long the mer stayed asleep, but he managed to do several quite good sketches of his anatomy before he woke up. He was studying his secondary set of fins, poking gently at them with the end of his pencil when the tail finally shifted in front of him. “What are you doing?” the mer’s voice wasn’t necessarily aggressive, just a little annoyed, but he still stiffened.

“Uh… I’m drawing you.” The mer looked at him, one eyebrow raised and he sighed. “You don’t know what that is, do you?” he asked and the mer thought for a minute, before shaking it- his head. He showed him the sketches and was surprised when the mer shifted closer, looking at them curiously.

“That is me?” he asked, carefully, moving to take the book.

Jason pulled back a little. “Yeah, but, uh, careful, you’ll get the paper wet.”

The mer’s eyes narrowed. “Why?”

Jason shrugged. “Dunno, that’s kinda just how paper works-” his brain nudged at him, exasperated. “Oh, you mean why am I drawing you?” The mer nodded and Jason thought about it. It was just something he liked to do, but he had the feeling the creature wasn’t going to accept that answer. “I’ve never really got a good look at a mer before, well, at least not without them trying to kill me… I thought it’d be worth documenting.”

The mer rolled his eye. “Humans.” he snorted derisively, but Jason couldn’t help but notice how his eye kept on wandering back to the sketchbook and the way he held himself changed to be more poised when ever Jason started sketching again. Jason had to hold back laughter, when the mer almost slipped from the edge of the pool he was resting upon because of his constant glancing at Jason and his book.

After a while, Jason took off his uniform jacket and lay it down on the flat rock, to dry completely, along with his sketchbook. He set off exploring the cave, noticing for the first time how big it actually was. There were little caves going off from it, none with exits he could use, but pretty interesting none the less. In one room he found what he could only describe as treasure. The mer had obviously been collecting it all for a long time, because a lot of the items looked very old, rusty and generally bashed up. Coins and weapons mainly, more disturbingly human skulls, too, there was even something that looked like a toy you’d give to children and something carved on the side that Jason recognized as Mermish. Inside a chest, Jason found a large number of long, braided ropes of what could only be hair. Trophies from Deathstroke’s fights with other mers, probably. Jason stared at the braids. Yeah, that was a little worrying, but he supposed it meant the mer could hold his own in a fight. After routing around a little more, he found a whale tooth, another toy, this one had a tiny lock of golden hair tied to it and a necklace that Jason recognized. It was something that mers used to signify that they were mated. A bit like wedding rings. He felt a little guilty after finding it, he couldn’t imagine that the mer would want him poking around in his possessions. The necklace was very beautiful, though, woven from a strong sort of algae and with a grey-blue scale at it’s centre. Deathstroke’s mate’s scale, probably, Jason thought, but shook his head. No, the mer would be wearing it if he was mated. Maybe they’d had a fight, or she’d died? Something in his chest tightened. He knew mers usually mated for life, something really bad must have happened to separate them.

He made his way back to main cave to find the mer hunched over the flat rock, he had Jason’s sketchbook in his hands. Jason almost moved to take it from him, but he saw that there were wet handprints on his jacket. The mer had dried off his hands before picking it up. So, cautiously, he came up to sit beside the mer, who looked at him briefly, something a little odd in his single eye, before turning back to the book. “These are very accurate.” he said, turning another page and Jason, not expecting the compliment, looked down to see that he was looking at the drawing he had done of a beached whale a while back. “The ones I know of, at least. The others don’t seem like they’d survive in the ocean.” The mer pointed at a drawing of Jason’s old cat.

Jason grinned. “Yeah, those ones really hate water, actually. They’re called cats.” The mer pursed his lips, eyeing the feline with suspicion.

“Cats… I don’t like them.” he said, finally and Jason did laugh this time.

“Figures.” he chuckled at the mer glared at him, putting the book down. Jason gulped, backtracking. “Okay, no, I’m not making fun of you, it’s just that cats eat fish, so… I dunno, I thought it was funny.”

The mer relaxed a little and so did Jason. They sat there in silence for a while, Jason not really sure what to say. “What is your name?” the mer asked, finally and Jason looked at him, slightly confused. Names meant a lot in mer culture, he’d read that much. If you give someone your name then you give them your trust, that kind of thing.

“Jason.” he answered, slowly, raising an eyebrow. The air felt sort of tense and he didn’t really tell why.

“Jason...” the mer tested the name carefully. “Does it mean anything in your tongue?”

“Uh, no. I don’t think so. Just a name.”

“Hm. My name is-” the mer said something in his own language that Jason had a hard time keeping track of.

“Slade?” he asked, cautiously, trying to mimick the sounds and the mer laughed.

“Close enough.”

“So your name isn’t actually Deathstroke, then?”

Slade’s eyes narrowed and he snorted. “Why would I have a human name? Such a stupid one, too.”

Jason shrugged. “Okay, yeah, I guess that doesn’t make sense.” he paused, before asking. “So, does your name mean anything?”

“Yes.”

Jason waited for an explanation, but it didn’t come, so he breathed out, saying “Okay, then, good talk.” and standing up.

The mer shifted beside him, looking like he was thinking about something. Jason honestly didn’t know if he should be worried or not, but that answered itself pretty quickly, when he was pulled to the ground and pinned down by Slade’s weight. “Jason.” the mer purred, something hungry in his single eye.

Jason shivered, eyes wide, before snarling. “Okay, no! We’re not fucking doing this again!” he yelled, pushing at the mer. “You’ve already made me fear for my life yesterday! Give it a fucking rest, would you?”

“I said I will not kill you.”

“Then what the hell are you doing?”

The mer cocked his head to one side. “Ah… So humans do not do this when courting?”

Jason froze. “Wait… I’m sorry? What? Courting?”

“Yes. The dominant mer shows they are stronger during courting, so that the other knows they will be protected.” Slade answered, as though he were talking about the weather and Jason gaped at him.

“No… Humans don’t do that. Not like this, anyway… Uh.” Jason’s brain was trying and failing to keep up with this and he could feel a headache coming on. “You know I’m not a woman, right?”

The mer shrugged. “I have already had offspring. I do not need others.”

“That’s great for you. Just checking.” Jason deadpanned, lamely. What the hell was going on? Sure the mer had been acting sort of touchy-feely, but he didn’t expect him to fancy him. Especially not like mer’s do. He was only seventeen, for fucks sake. The creature couldn’t possibly think he was ready for a life-long relationship with someone he’d only just met. Anger rose in him and he glowered at Slade. “You know what, though, I think I’ll stay a bachelor. You’re a bit too fucking grabby for me.” He pushed at the mer and this time Slade did actually get off him, looking confused and maybe even a little hurt.

“But why?” he asked, following Jason as he got up and limped over to the wall to cool off.

“Why?” Jason looked at him incredulously. “You’re not exactly well-known in the human world for being very nice, Slade! You’ve killed thousands of goo- sort of good humans and come very close to killing my older brother and the only father figure I have!” he pinched the bridge his nose, trying to calm himself down. “More over, I don’t know you!”

Slade looked very confused now. “I don’t see why my killings should effect this. If anything they are a sign you will be well looked after. Although, I do apologize for hurting your kin. As for knowing me, is that a human requirement? I know enough of you to know that I enjoy your company and that you are beautiful and quite strong for a human. You would make me a good mate.”

Jason stared at him. “Seriously? Is that what love is to you creatures? Someone you can tolerate to look at and talk to and who isn’t completely useless at physical combat?”

“Mating is not about love, Jason. But we expect it to grow from that. Once the mind is open to love someone it often happens.” Slade explained, as though talking to a child.

“Is that why you’ve got that discarded mating necklace in that stash of yours? Did you two love eachother?” Jason knew he’d gone too far the minute he uttered the words, but the hiss that came from the mer told him he’d royally fucked up. That armoured tail smashed into his stomach a few seconds later and he was thrown against the wall, winded, before sliding down it, with a groan. Slade was on top of him in seconds.

“Do not speak of what you have no understanding!” the mer hissed into his face, his teeth bared and eye narrowed into a slit. He gripped Jason’s throat so hard that he choked. “Adeline and I were-” he broke off and drew back, a mixture of rage and shame on his face. Jason watched him, watched the way his chest rose and fell, the way his jaw tightened and his fists clenched, the way his tail fins beat distractedly at the floor in frustration. He disappeared into a pool in seconds and Jason was left to breathe raggedly and look out into the cave. He’d definitely struck a cord there, then.

Jason could barely sleep that night. With Slade gone and having slept very well the previous night he couldn’t help but letting his mind race through the events of the day. Why did Slade think that after two days of knowing each other he could, as he put it, court him? It seemed like insanity, but he supposed he couldn’t really fault the mer with his logic. There probably wasn’t much room for romance in mer society, partnerships like that seemed like they were meant for survival, rather than anything deeper. But still, Slade could definitely take care of himself, so why did he want anyone else. His mind drifted to the way Slade had held him that morning, it hadn’t exactly been overly comfortable, but he’d obviously made an effort to be gentle. Maybe he wanted someone to care for? Jason drifted off to sleep eventually, but it seemed like only seconds before the sun woke him again.

He found a small pile of dead fish next to his rock and noticed that the guts and bones had been removed delicately. Slade must want him to eat them, he thought, feeling both annoyed and grateful. He’d been hungry for a while, so why was the mer only really caring about that now? Trying to soften him up so he could try and court him again? Jason would like to say he’d never eaten raw fish before, but he’d be lying. When he was on the streets in Gotham, the fish market by the harbour was sometimes the only place he could get his food and it wasn’t as though he’d had a proper home to cook them in. So he did eat the fish and he waited. He waited the whole day for Slade to return, but he didn’t. When he finally drifted off to sleep again he almost felt bad. The mer was obviously really annoyed at him.

It wasn’t until midday, the next day that the mer showed himself. Jason only even noticed he was back when a salmon hit him on the back of the head. “Ouch! For fuck sake!” he growled, turning to see the mer leaning over the side of the pool. He looked amused. Which was… Good?

“Eat.” he said, simply and Jason did, because, yeah, he was hungry again. And no, he wasn’t trying to make Slade happy.

“You’re back.” he said, once he’d finished, wiping his mouth on his sleeve.

“This is my home.”

Jason nodded, dumbly. “Yeah, right...” He looked the mer in the eye. Slade looked down, before returning his gaze and Jason was thankful that he could at least look at him. “I thought you’d left me here to die, to be honest.”

“I said I wouldn’t kill you, did I not?” the mer’s tone of voice was softer than Jason had heard it before and he pulled himself up onto the edge of the pool. Jason thought of pointing out that letting him starve would be manslaughter, not murder, but stayed quiet, waiting for Slade to speak again. “I have a proposition.”

“Okay?” Jason said, cautiously, his hands nervously playing with the hem of his jacket.

“If a human tries to swim through the tunnels beneath us, they would die, we both know this.” Slade began and Jason grimaced, about to interrupt him, before he continued. “But if I were to pull you through, you may reach the other side still alive and well. You may find your kin again, too.”

Jason thought about this. He’d seen how fast mers could swim and if they could out-swim a ship, Slade might just be onto something. “Yeah, I suppose that could work.” he frowned, glancing at the mer suspiciously. “And what do you want in return for pretty much saving my life?”

Slade paused, as though unsure of how to phrase his demands. “I wish to court you.” Another pause, then he added “For a considerably longer time than I would court a mer, mind you. I trust that would also fall under remedying the ‘not knowing me’ objection you have.”

Jason stared at him, thinking quickly. “And if I don’t want to be your mate after you’ve courted me?”

“That is your decision to make.”

The lieutenant bit his lip and sighed, he looked at Slade, then up at the fucking hole and back. “Okay, yeah, sure. It’s a deal.” Slade moved to grab him again, but Jason took a step back. “But I have some conditions.”

The mer rolled his eye. “Yes, very well. What are they?”

“You’ve got to stop this whole grabbing thing while you’re courting me.” Jason pointed out. “Just ask me to come with you, or to sit down, or whatever, don’t pin me.”

“Yes, fine.”

“And you’re not allowed to hurt anyone from my fleet.” he thought of Captain Sionis briefly and added. “Unless I ask you to.”

The mer smirked at this and nodded. “Very well.”

“And none of my fleet can see you with me.”

The mer considered this. “That will make things more difficult, but I’ve grown quite good at avoiding humans, I suppose. I agree.”

“Okay, yeah, I think that’s it.” Jason finished, his heartbeat a lot faster than it was a few minutes ago.

“Well, then, could you get in the water, please?” Slade was obviously mocking him, but Jason was still grateful that he hadn’t been pulled into the pool by force. He crouched down and gently lowered his bandaged leg into the water, before hopping in. He’d been right, it was a lot deeper than it looked, but Slade caught him, before his head could sink underwater and Jason stiffened. It was one thing to have the sleeping mer halfheartedly cuddle him, but quite another to feel the actual strength of those arms, holding him up effortlessly in the water. “Deep breath.” the mer said and Jason looked at him, shocked.

“Wait, we’re going to do this right now?”

“Yes, Jason.” Slade said, exasperatedly.

“Hang on for a fucking second. I need to calm down a bit, okay?” Jason took a few deep breathes, trying really hard not to think about what drowning would feel like. He finally sucked in a gulp of air and nodded at Slade.

They were speeding down the pool and into a small tunnel mere seconds after that. Everything was dark and all Jason could feel was the pressure of water and Slade’s body pressed against his own. After a few more seconds he started to panic. He couldn’t see anything any there was no sign of an exit as Slade twisted and turned through the darkness. Eventually, they hit a bump and Jason felt the air being pressed out of his lungs. Oh fuck. This was it. This is how he was going to die, killed by falling down a hole and accepting the help of a mer… What a perfect ending to the trainwreck that was his life. Then, lips, smooth and commanding, latched onto his own and cool air was pushed back into his lungs. He wasn’t going to die. Fucking hell. He wasn’t going to die! He could see light up above them and then they were breaking the surface and he was gasping air in and out of his chest, clinging to the arms holding him up for dear life. He felt like punching the mer, or kissing him, he really couldn’t think which, but Slade decided for him and their lips met again. And Jason… Jason kissed back. He wrapped his arms around the mers neck and pressed himself against him, shuddering as their mouths moved against each other.

Slade finally pulled back and Jason stared up at him. “You almost fucking killed me back there!” he accused, half-heartedly punching the mer’s shoulder.

“Yes, my apologies, I didn’t expect us not to fit around that bend.”

“Okay, right. Well, thanks for helping me breathe again, I suppose.” Jason shivered. “Uh, could you maybe swim me to the beach, please?”

“Of course, beloved.” Slade began to move, holding Jason close as they headed towards the rocky shore.

Warmth spread over Jason’s cheeks at the word, but he didn’t complain. It felt kind of nice to be called that. Not that this whole courting thing would work out, but still. It felt nice.

._.

Bruce had been furious. Furious and, as Dick pointed out later, really worried. They’d started looking for him the minute Dick had gone to see why he wasn’t there to perform his duties in the morning. He’d been teased no end by Roy, Dick and Tim about getting himself trapped in a cave, but they’d all bought that he’d managed to climb out, even with an injured leg. Everyone except Alfred and Bruce had bought it, that is, but Jason was pretty sure Alfred was psychic and Bruce was just naturally suspicious of everything.

So he’d been assigned night watch duty for the next month and they’d sailed as far as they could from the island. Honestly, this suited Jason just fine, though a part of him wondered if Slade would be able to follow him. Not that he cared, of course.

That was answered on his third shift of the night watch, when something hit him in the back of the head. Hard. He swore and clutched at the sore spot, turning around to look behind him. Lying on the deck behind him was a watertight pouch. His watertight pouch. He scrambled to pick it up, unlocking it and looking inside. His sketchbook was nestled, undamaged in it’s folds and he grinned. He moved to look over the side of the ship and sure enough hi- the mer was looking up at him, his own scales barely distinguishable from the water, save for the way the light hit them and the way his single blue eye glowed and silver mane shone among them. “You know, if throwing stuff at my head is your idea of courting, then I might have to rethink this!” he whisper-yelled at Slade.

The mer bared his teeth is a smug grin and answered. “Oh no, that was what I think you humans like to call teasing.”

“Yeah?” Jason asked, snorting. “You might have to work on that, too. So, when does the courting start?”

“Right now.” Slade leapt into the air, copper edged scales shining in the moonlight, before he hit the water gracefully, he leapt up and dove into the sea, flicked his tail at Jason, puffed his gills and it took the lieutenant a moment to realize that the mer was dancing. He was dancing for him. Jason leant against the railings and watched the show. It really was quite beautiful, he had to admit, flattering too. Not that this could ever work out. Of course.

Later, when he was looking at the sketches he’d made of Slade, for research purposes only, he noticed one, rather torn page, was covered by a crude drawing of a human, the name JASON, scribbled next to it. He hugged the book to him in his hammock, grinning stupidly at the ceiling.

._.

The pirate Red Hood became a legend across the seven seas, stealing from other pirates, killing those who hurt the innocent, or occasionally those who got in his way and sometimes even giving his treasures to those most in need of it.

Even naval officer Bruce Wayne, King Kal-El’s right-hand-man, had a hard time containing him and it wasn’t hard to see why. The people of DeeSea loved and feared him and some even whispered there was a curse that fell on anyone stupid enough to cross him. They’d disappear mysteriously, they said, as though swallowed up by the ocean, or they’d be found with savage gashes covering their bodies.

Meanwhile the legends of Deathstroke, the killer mer, became stories mothers in Gotham would tell their children to make sure they didn’t run away to sea. Red Hood, however, only grew more popular as time went on. There were rumours that he had won the hearts of the two warrior princess that would fight by his side on occasion and that one of them had given him a betrothal necklace. A red band of leather, with a shining black and copper coloured jewel in the centre. His second-in-command and armourer Arsenal ,would laugh whenever new recruits asked him about it and tell them their captain had won it off a mer a long time ago.

**Author's Note:**

> I hope you liked that fic! I'm honestly not sure about it, I liked the idea, but if you have any tips for the execution, let me know! Or just let me know what you thought in general!


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